Highlights: Dimensions : 16" x 20" x 1" Filter Material: Spun Fiberglass Minimum Efficiency Reporting Value: 4 MERV Filters Dust Filters Pollen Filter Frame Material: Moisture Resistant Die Cut Chipboard The frame is made with one continuous piece of chipboard to guard against corner separation and is strengthened by a metal retainer The filtering medium is continuous filament spun glass Sandard grade furnace